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PROJECT PLASTIC 2018 candidate: Technological signature in precision injection compression moulding of polymer Fresnel lenses

The optimisation of injection-compression-moulding in Fresnel lens production enhances the replication quality of polymer optics. For the task, the use of optical metrology leads to innovative ways to manufacture plastic products.

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Fresnel lenses are optical components designed with concentric grooves which enable reduced dimensions and enhanced light gathering properties with respect to conventional aspheric lenses [See FIG.1 below]. For these characteristics, the demand of Fresnel lenses in electronic devices, especially smartphones flashlights, in automotive lighting, and in other optical applications is increasing.

The use of polymer instead of glass, makes the optical parts cheaper, but the transparency and the crystallinity must be accurately considered during production.

Moulding technologies exploit a hard metal mould to massive replication of plastic amorphous polymer parts on them. More precise, accurate and productive processes reduce cost and increase functionality of polymer optics.

In this master thesis project, Injection-Compression-Moulding (ICM) has been used and optimized [See FIG 2 beloe] to understand the technological signature of the moulding technique to the polymer Fresnel lens geometrical dimensions [See FIG 3 below]. The understating of how the functionality of the lens is affected by its geometrical characteristics is the natural evolution of this project.

On these topics, two conference papers and two journals articles are under review.

 

University and the academic level of the project:

Technical University of Denmark 30 ETCS M.Sc. Thesis Project in Mechanical Engineering
converted at
Politecnico di Milano 20 ETCS M.Sc. Thesis Project in Mechanical Engineering

 

Which type(s) of plastics/production processes are used in your solution?

Polymer optics, Fresnel lenses, Injection compression moulding, Optical Metrology.
COP – Cyclo-olefin polymers
PMMA – Polymethyl methacrylate
Injection Moulding
Injection Compression Moulding

 

More information

 

Figure 1. Collapsing a conventional aspheric lens design to a Fresnel lens. [Arthur Davis and Frank Kühnlenz. Optical Design using Fresnel Lenses, Basic Principles and some Practical Examples. Optik and Photonik, Wiley, (4):52-55, 2007.]
Figure 2: Moulded Fresnel lens, CAD Design and Mould equipment.
Figure 3. Measuring the Fresnel lens with optical metrology

PROJECT PLASTIC is a talent competition for engineering students. The purpose is to celebrate the talented students that as part of their degree lead the way in how to use plastic materials to create innovative solutions. The competition is being administrated by The Danish Plastics Federation.

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